WASHINGTON (AP) — Already bruised by an earthquake that damaged two of its iconic structures, the nation’s capital was watching and waiting Saturday for its first hurricane in more than a half-century, a storm that could test its ability to protect both national treasures and vulnerable residents.

The worst of Hurricane Irene was supposed to hit Washington late Saturday night and early Sunday morning. Forecasts called for several inches of rain, wind gusts of up to 60 mph and possible flash flooding. The expectation led organizers to postpone the dedication of the Martin Luther King Jr. Memorial on the National Mall that was expected to draw up to 250,000 people.

But beyond the tourist mecca of the Mall, the District of Columbia is a diverse city of 600,000 with a stark divide between the wealth of Northwest and the poverty of Southeast. And in the impoverished neighborhood of Anacostia, many weren’t prepared for the storm — and weren’t assured that the district government would do much to help them.

The district is constantly on guard against terrorist attacks, but some residents say it remains ill-prepared for disasters. People leaving the city after this week’s 5.8-magnitude earthquake — which caused cracks in the Washington Monument and millions of dollars in damage to the National Cathedral — snarled traffic for hours.

“I don’t think Washington is equipped for a big storm or evacuation or anything like that,” Melvin Holloway, 61, a retired District of Columbia water department employee, said as he sipped from a can of Bud Light outside a convenience store Saturday morning. “There’s just no communication.”

Flooding is one problem. City leaders last fall recognized that the National Mall along the Potomac River was vulnerable during a massive storm and started a project to upgrade the system of levees along the river. Construction has started but will take several years to complete.

Built on the banks of the Potomac on swampy ground, Washington has always been under threat of river flooding from a major storm. A U.S. Army Corps of Engineers review after 2005’s devastating Hurricane Katrina concluded the city’s flood-control system — built some 70 years ago — was inadequate.

A map of potential flooding by the Federal Emergency Management Agency said museums such as the National Gallery of Art and federal buildings like the Commerce Department could be under as much as 10 feet of water if the current flood-control measures failed. That triggered planning for a better system.

This week, the city struggled to distribute sandbags, with hundreds of cars lining up for up to two hours to collect them. By about 3 p.m., the city had nearly run out. It gave away about 13,000 bags over two days to a cross-section of the population. Many were homeowners looking to protect their basements.

“They should have done it earlier,” State Department employee Tina Harris, 36, said as she snaked toward the front of the line in her minivan early Saturday afternoon following a wait of about an hour and a half.

At the same time, Harris, who lives in the Northeast quadrant of the city, which is not as vulnerable to flooding, said it was unrealistic for Washington to prepare adequately for a hurricane.

“We haven’t had one before. We’re not used to it,” she said.

The last named storm to cause damage in Washington was Isabel, which had weakened to a tropical storm when it hit in 2003. The last hurricane to hit was Hazel in 1954.

As for where people live, despite being built on two rivers, the district has relatively little waterfront housing, although certain neighborhoods, including wealthy Georgetown and the Southwest Waterfront, are susceptible to flooding. The waterfront has mixed demographics, but there are public housing complexes and lower-income neighborhoods near the water.

The district will be keeping its homeless shelters open for the duration of the storm, and had also set aside four places for displaced residents. By Saturday evening, those temporary shelters had yet to open.

The poorer sections of the city are always a worry, said Councilmember Marion Barry, the former four-term mayor. He represents Ward 8 — the poorest of the city’s wards — and said his constituents were accustomed to bearing the brunt of bad weather and other adversity.

“Whenever there’s an outage, we’re going to be the first,” Barry said. “We’re the first, and we get hit the hardest.”

Homes in Ward 8, however, are unlikely to be flooded by a surging Anacostia River, because the riverfront is occupied by a park and by Bolling Air Force Base.

Much of official Washington has considered the possibility of a once-in-a-generation storm.

For example, the monuments along the Tidal Basin — including the Jefferson Memorial and the new King Memorial — are designed to withstand flooding, said Bill Line, a National Park Service spokesman.

Line said he did not believe the Tidal Basin — a manmade inlet off the Potomac River walled off by a stone embankment — had ever overflowed its banks, although he conceded it was possible in an incredible storm surge. Much of the National Mall was created by a massive Army Corps of Engineers dredging project more than a century ago that altered the path of the Potomac River. There was not damage by Saturday night.

The National Archives installed self-rising walls to protect the building after severe flooding in the basement damaged a newly opened theater, said spokeswoman Susan Cooper. The walls have worked in past storms, she said. The building doesn’t keep its precious documents in the basement.

Pepco, the utility serving the district and its Maryland suburbs, warned customers that Irene could bring destruction and that restoring service could take several days.

Millicent West, the city’s homeland security director, said officials from several agencies would be making the rounds in poor neighborhoods to make sure residents weren’t neglected. Mayor Vincent Gray said that given forecasts showing the storm moving out by Sunday afternoon, he did not anticipate vulnerable residents being isolated for days in dangerous conditions.

“We hope that the duration of this will be relatively short, which means that people can get back out and get engaged in the normal patterns of life,” Gray said.

Ward 8 has a 25 percent unemployment rate and a 35 percent poverty rate. In Anacostia, some residents were making do with what they had, which wasn’t much.

“I’m just about as ready as I can get,” said Patricia Williams, a resident of Barry Farm, a sprawling, rundown public housing complex. “I don’t have no money to stock up on water and food.”